We are allergic to exploiting great solutions that already exist. Everyone wants to be "disruptive".
It reminds me of the investment that went into hyperloop stuff when our current best transit solutions aren't anywhere close to full saturation in the US. Similarly our current best green technologies are far from being fully exploited.
The liver is one of the most complex organs in the human body. It is responsible for a wide spectrum of toxin breakdown and chemical synthesis. The heart only needs to pump blood, though it's uptime is very impressive. If your liver stops working you won't die immediately but if your heart stops working your body will be starved of oxygen in mere minutes. Ultimately though what the heart does is mechanical and simple.